Saturday, October 4, 2014

This blog has been quiet while I made a move from being a professor at the University of Michigan Medical School to Arizona State University, where I now lead a new Center for Evolution and Medicine. I remain fascinated by how hard it is for people to think clearly about evolution and adaptation, but I need to change my focus to evolution and medicine, so that probably means a new blog at a site with a less interesting name.However, much of the fascination of evolutionary medicine comes from realizing that a lot of things that seem like problems are actually useful traits shaped by selection. Fever, cough, pain and anxiety are just a few examples. The problem is that the human mind seems wired to classify things in terms of their functions, so people think up functions even for dire diseases like cancer and schizophrenia. And this leads some whose minds tend towards generalization and stereotyping to criticize the whole effort to apply evolution to medicine. So human a response! But it is hugely problematic for a field where sober thinking about adaptive significance is so lacking and can be so helpful. The solution is simple. Don't generalize about evolutionary medicine. Judge each hypothesis based on the evidence for and against it. This turns out to be difficult. My students find it hard even after a full course. I wrote a paper that offers a cookbook approach to avoiding the main mistakes. Ten questions for evolutionary studies of disease vulnerability, Evol Apps, 2011Some have found it helpful. But I think I will follow my own advice and switch soon to blogging about specific hypotheses. In the meanwhile, do come to the March 19-21 inaugural meeting for the International Society for Evolution, Medicine, & Public Health!

Tuesday, July 30, 2013

The Crooked Crabapple Tree featured in a previous post is misshapen from coping with early adversity, but fundamentally healthy and growing fine . The Tenuous Tree below, at the Pictured Rocks National Lakeshore, looks perfectly fine, but it is hanging onto life by its fingernails...or, rather, by only two roots. They almost certainly have gotten bigger as the demands placed on them increased because soil, rock and other roots were pummeled away by the waves. But the least disruption to these lifelines will spell the end for this glorious tree.

Saturday, July 20, 2013

I was sitting on my dock, looking at the water, trying to figure out why schools of
thought are so insular. Schools of
minnows provided the answer.

It is no secret that academic fields have rigid
boundaries. Quiet insularity would be bad enough, but many
are belligerent towards other groups, especially others that claim the same
territory. Philosophy, literary criticism, and history each have many competing schools of thought. Social, cultural, biological,
clinical, behavioral, cognitive, personality, and developmental psychology are remarkably
separate fields. Cultural and biological anthropologists
hardly talk. Science and postmodernism repel
each other as if each had arrays of magnets with north poles facing outwards . Everyone knows the world would be better if
boundaries were more blurry, but interdisciplinary programs come and go, and schools of thought maintain their insularity. Why?

I watched a school of minnows swirling in the shallows, flashing silver in
gorgeous unison, splitting, then merging, then splitting and merging again. No choreographer could enforce such gorgeous coordination, but it emerges spontaneously from each minnow swimming steadily towards the constantly moving center of the school. How did selection shaped minnow brain wired to motivate swimming towards the center? As I watched,
one minnow turned right when the group turned left; it was alone for one second,
then it was grabbed by a bluegill.

Humans who stray from the centers of schools of thought don't get snached by predators, but they are often attacked by other humans who are safely within groups, making the territory outside a no-man's-land. Has this
been happening long enough to shape a general tendency to move mentally towards
the ideological center of a group?
Or do we all just learn, from experience, that deviation is
dangerous, but nonetheless tempting, and sometimes worth it, because the most fertile ground is between the silos.

Wednesday, June 12, 2013

Every day as I walk to work, I see a crabapple tree, lopsided and misshapen. Leaning far over the road, bereft of branches on the other side, it seems, like so many people, to be trying, but failing. What can cause such distortion? Perhaps bad genes? Hidden from view is the stump of a huge hickory tree, just a bit further from the road. In its shade, the poor crabapple was doing the best it could, growing towards what little light it could glean. Now in the sun, it blooms, but it will always be crooked.

The Nature article notes that the radioactive isotope iron 60 does not form on earth. The tiny amounts found in seabed sediments come from supernova explosions. The Munich physicists Shawn Bishop and Ramon Egli wondered if the event could be dated. Sure enough, iron 60 was found only in sediments from exactly 2.2 million years ago (Bishop, S. & Egli, R. Icarus 212, 960–962, 2011, perhaps coming from a supernova in the Scorpius–Centaurus stellar association to be incorporated into magnetotactic bacteria in the sea. By happenstance, these events occurred at the very time when modern humans were first emerging. This is interdisciplinary science at its best!

But, doesn’t it make you wonder why some bacteria have special machinery to synthesize magnetic particles? One clue is that they tend to be anaerobic bacteria that live near a boundary with oxygenated water. Their magnetic crystals align them with the earth’s magnetic field, so they can swim only along the earth’s magnetic lines. How could that help, given that the earth’s magnetic fields go north and south? In the northern hemisphere, the magnetic lines dip downwards into the earth, so by turning their flagella counter clockwise and swimming straight towards the pole, they can reliably dive to deeper depths where there is less oxygen. In the southern hemisphere, the magnetic lines go up instead of down...so to get to the depths and away from oxygen, bacteria that evolved there swim away from the pole.

Wednesday, April 27, 2011

The fundamental attribution error is pervasive. On yesterday's walk, our black standard poodle, Lucy, simply would not heel. I held a dog biscuit in my left hand, usually a surefire cure for bad behavior, but she insisted on roaming to the right, where my wife was walking. I quickly came up with an explanation, "She's always liked you better." Margaret agreed, "Yes, I spend more time with her and I feed her."

I ran out of dog biscuits, so I asked Margaret if she had any. She gave me her bag of treats, tiny bits of liver biscotti, Lucy's favorite. Everything changed. Now Lucy paid no attention whatsoever to Margaret. She heeled perfectly, her eyes riveted to my left hand, waiting, salivating. Lucy's behavior had nothing to do with her love for Margaret, and everything to do with who held the liver biscotti.

Why do we so readily attribute behavior to enduring traits and neglect the power of the situation? I suspect it's because over the past few hundred thousand years, information about what individuals are like has been enormously useful. People, and dogs, have personalities that stay remarkably consistent for decades. Attending closely to what people are like, coming up with theories about their traits, and gossiping about them has been important. Using theories about persons to explain behavior comes naturally, so naturally that we routinely underestimate the power of the situation.

Friday, September 10, 2010

George C. Williams died on September 8, 2010 at the age of 84. One of the most important biologists of the 20th century, his influence came not from big grants, flashy talks, magazine articles, or scores of graduate students. Instead, he pursued methodical thinking about important questions and distilled his conclusions into crystal clear prose. His approach was consistent. He would be struck by some apparent contradiction between fact and evolutionary theory, and work on it until a resolution emerged. Senescence, sex, menopause, and vulnerability to disease, all are hard to explain in evolutionary terms. In each case, he thought and thought, eventually coming up with a major contribution.

Friday, October 3, 2008

As often noted, it is senseless to ask whether a trait is caused more by genes or more by environment. Like the length and width of a rectangle, both genes and environment are essential to the development of any trait. However, if the task is to explain variations in a trait, then the same analogy holds--the area of the rectangle changes only if its width or length (or both) changes. Variations among individuals can result only from differences in genes, differences in environments, and the interactions between them.

Tuesday, July 29, 2008

Constructive engagement is rare, not just in political seasons, not just in our society, but always and everywhere, for good evolutionary reasons. Understanding those reasons gives us a fighting chance to avoid useless fighting and begin constructive engagement.

By constructive engagement, I mean people trying as hard as they can to express their own ideas clearly, to understand other people’s beliefs and their reasons for those beliefs, to understand the exact differences between the beliefs, and to specify and search out information that would resolve any differences. Far more common are two patterns of unconstructive engagement, which can be caricatured as the mutual admiration society and the war of the clans.

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About

Nothing is more interesting than adaptations shaped by natural selection. Except, possibly, maladaptations that leave us vulnerable to disease. This blog is about the challenge of testing hypotheses about adaptation. Many posts are about Darwinian medicine, psychiatry, emotions and moral capacities.For a more formal journal about evolution and medicine, see The Evolution and Medicine Review.